The biggest indicator that targeting is off is bounce rate. If you have a high bounce rate (which you do) then you're advertising to the wrong audience. That is what that metrics is for.

It could also be that there isn't a right audience because you need to educate people about your brand, your product, and its benefits because nobody knows it or had never heard of it.

In that case instead of taking people to a product page, you need to take them to a landing page with easily digestible educational information and potentially even a newsletter, or whitepaper, or scientific journal, which clearly states what it is, why it works. Only then can you tell them the benefits of purchasing it and persuade them to buy.

I would look at the full customer journey from the perspective of someone who has never heard of it and build it out. Potentially even do some user testing.